英文:
Golang: How to declare returned variables WITH TYPE?
问题
在Go语言中，你可以使用短变量声明来声明函数的返回变量，并指定它们的类型。以下是你想要的代码示例：
var dat []byte
var err error
dat, err = ioutil.ReadFile("/tmp/dat")
check(err)
fmt.Print(string(dat))
这样你就可以在声明变量的同时指定它们的类型。希望这可以帮助到你！
英文:
In GO, how do I declare the returned variables of a function WITH TYPE ?
e.g. I have this code
dat, err := ioutil.ReadFile("/tmp/dat")
check(err)
fmt.Print(string(dat))
but what I want is this:
var dat []byte, err error := ioutil.ReadFile("/tmp/dat")
check(err)
fmt.Print(string(dat))
However, no matter how I try, I only get this output
> syntax error: unexpected comma, expecting semicolon or newline or }
I'm working without IDE, and as the number of variables increases, it's really idiotic to have to keep all the return values's types in short-term memory... let alone if somebody else has to read the code.
How can I declare the returned tuple WITH type ?
答案1
得分: 4
这是因为你在赋值时使用了:=，这是一种方便的语法用于声明和赋值。它使你不必提供类型，我猜编译器会根据右侧返回的内容/任何类型来推断类型。相反，你需要这样做：
var dat []byte
var err error
dat, err = ioutil.ReadFile("/tmp/dat")
但是很少有人这样做，因为dat, err := ioutil.ReadFile("/tmp/dat")是一种更简洁的语法。
英文:
That's because you're using := in your assignment there and that is a convenience syntax to declare and assign. It makes it so you don't have to provide the type, I assume the compiler just implies it by what is returned/whatever types come from the right hand side. Instead you need to do this;
var dat []byte
var err error
dat, err = ioutil.ReadFile("/tmp/dat")
But no one does this because dat, err := ioutil.ReadFile("/tmp/dat") is such a cleaner syntax.
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